MySQL

1. Select the appropriate field properties. For example, when you define a postal code field, if you set it to char (255), you obviously add unnecessary space to the database, and even this type of varchar is redundant, because char (6) can do a

A vertical table to the horizontal table1. Create a vertical table firstCREATE TABLE Student (ID varchar (+) primary key,Name varchar (NOT NULL),Subject varchar () NOT NULL,result int);2. Inserting dataINSERT into student (ID, name, subject, result)

Modify the syntax of a tableCreate two tables First:Table I: Tbl_department Department table CREATE TABLE tbl_department ( dept_id Int (ten) is not null unsigned auto_increment,Dept_name varchar () NOT NULL,Dept_describ varchar (100),Primary KEY

# 1. Stop the MySQL process [[email protected] ~]#/etc/init.d/mysqld stopshutting down MySQL ... success! [[email protected] ~]## 2.mysqld_safe configuration Skip Authorization table start mysql[[email protected] ~]# mysqld_safe--skip-grant-tables --

Summary of the differences between collation Utf8_unicode_ci and Utf8_general_ci in MySQLAfter such a long time, found that they do not know Utf_bin and utf_general_ci the difference between the two exactly.CI is case insensitive, that is, "casing

MySQL version: 5.6.36Xtraback Edition: Version 2.4.61. Modify the master node MySQL configuration file and restart MySQLCat/usr/local/mysql/my.cnf[Mysqld]DataDir =/var/lib/mysqlSocket

User Management1. Query usersUse user;Select Host,user from user;2. Create userCreate user hkx001 identified by ' hkx001 ';Create user [email protected] identified by ' hkx001 ';Note: [User]@[ip] indicates that the user client must have an IP

I. MySQL database start-up and loginInstallation here will not elaborate. Remember to configure the installation path into the environment variable after the installation is complete. Then go to the command line to start the database. Note: When

##====================================== ===============## pt-osc Workflow: 1, check if the change table has a primary key or a unique index, whether there is a trigger Span style= "FONT-SIZE:14PX; Font-family: ' Courier New ', courier; >2,

1. First we need to bathe the installation package, now is 2017.7.9, currently the latest version for 5.7.18.1 I installed version of the computer is 32-bitDownload URL: https://dev.mysql.com/downloads/file/?id=4700912. Double-click the downloaded

After a char or varchar set length is exceeded, the string is truncated.The difference between char and varchar is that Char takes up n characters regardless of the actual value, and varchar consumes only +1 of the actual character space, and the

1.mysql InstallationThis installation is very simple, is installed online, only need to execute a few commands in order OK.(1) sudo apt-get install Mysql-server(2) sudo apt-get install mysql-client(3) sudo apt-get install Libmysqlclient-devThe

Experimental environmentTwo CENTOS7 MySQL5.7.12 IP addresses are: 192.168.10.36 192.168.10.37One CENTOS7 mycat IP address is: 192.168.10.31One: Install MySQL as shown here (yum installation is used here):Two: Configure MySQL, and build MySQL

1. Increase1 ImportPymysql as PS2 3 #Open a database connection4db = Ps.connect (host='localhost', user='Root', password='123456', database='Test', charset='UTF8')5 6 #Create a Cursor object7Cur =db.cursor ()8 9sql ="INSERT into USER (name,sex)

1. Download and unzip the MySQL5.6.36 compressed package (by the way, rename all at once).　　2. Copy the My-default.ini file to the name My.ini, and then modify the following red box callout 　　3. Install and start the service.Run cmd as administrator

1 ImportPymysql as PS2 3 #Open a database connection4db = Ps.connect (host='localhost', user='Root', password='123456', database='Test', charset='UTF8')5 6 #Create a Cursor object7Cur =db.cursor ()8 9 #parametric processingTensql ="INSERT into USER (

1. Send a message like a server database, add dataThe code for the WPF side:void SaveData()//Fang is a WPF-uploaded{if (Filesavename = = NULL | | filesavename = = ""){Savename savename = new Savename ();bool? SaveState = Savename. ShowDialog ();if

What to do if MySQL forgets the root passwordPassword MySQLIf you forget the root password or other user password, do not worry, just follow the steps below.1. Edit the MySQL Master profile my.cnfVim/etc/my.cnfAdd a parameter under the [Mysqld]

--linux Base configuration specifies that the machine name is SQL1--View the CentOS kernelUname-aCat/etc/issue--Modify Machine name1, echo "192.168.33.190 sql1 localhost.localdomain localhost4 localhost4.localdomain4" >>/etc/hosts2, Vi/etc/sysconfig/

Add a column to a column nameALTER TABLE table_name ADD column_name int after column_name;Change Column NameALTER TABLE table_name change old_column_name new_column_name int;Modify TypeALTER TABLE table_name MODIFY COLUMN_NAME float;Delete